Mourners held a candlelight vigil Wednesday outside the Baton Rouge, Louisiana, convenience store where police had shot and killed an African American man just 24 hours earlier - an incident captured on cellphone video that rekindled national outrage over alleged use of excessive force against African Americans and other minorities.

Large crowds had been gathering outside the Triple S Mart throughout the day to protest the death of 37-year-old Alton Sterling, waving signs and chanted "Black lives matter" and "Hands up, don't shoot," slogans heard after other fatal encounters between police and black residents.

Earlier Wednesday, Louisiana Governor Jon Bel Edwards announced the state was turning over the investigation into the shooting to federal authorities, led by the U.S. Justice Department's civil rights division. "I have very serious concerns," Edwards told reporters in making the announcement. "The video is disturbing, to say the least."

In this July 5, 2016, photo made from video, Alton Sterling is held by two Baton Rouge police officers, with one holding a hand gun, outside a convenience store in Baton Rouge, Louisiana.

Fatal confrontation

The video showed two officers initially confronting Sterling before tackling him and pinning him to the ground. They wrestled with Sterling for several seconds before someone yelled "He's got a gun." Both officers pull their weapons and point them into Sterling's chest, with one saying "If you f****** move I swear to God," before firing several shots.

Baton Rouge police chief Carl Dabadie told reporters that Sterling was armed when the officers arrived on the scene. But a video of the incident taken by the store's owner, Abdul Muflahi, and posted on the website of the Baton Rouge Advocate newspaper showed one of the officers reaching inside Sterling's pocket for an item after the shooting.

The officers, identified as Blane Salamoni and Howie Lake II, have both been placed on administrative leave.

A woman touches a makeshift memorial for Alton Sterling, outside a convenience store in Baton Rouge, Louisiana, July 6, 2016. Sterling was shot and killed by police outside the store.

‘Something is profoundly wrong’

Officials say police went to the store after an anonymous caller said they had been threatened by someone with a gun.

But Louisiana state Representative Edmond Jordan, an attorney for the victim's family, said "Mr. Sterling was not reaching for a weapon. He looks like a man that was actually fighting for his life."

The family and store owner Muflahi says Sterling, a father of five children, was a regular presence outside the store, selling homemade music CDs from a folding table.

Protesters stand on cars as they congregate at N. Foster Dr. and Fairfields Ave., the location of the Triple S convenience store in Baton Rouge, La., Wednesday, July 6, 2016.

Reaction to the shooting was swift after the cellphone video was posted on social media.